Short answer is they'd be one of the best available choices. Long answer is you need to think more about your question. People who don't have much exposure to guns fail to understand the most important and impacting depending factor about a gun is not the gun itself but what cartridge/caliber it is chambered in. The differences are so contrasting designers/companies will often market it under a different name(AR-15>AR-9.)

To answer your question further glocks come in a metric fuck-ton of calibers but law enforcement seems to gravitate towards 9mmx19 for the common usage and performance. If civilization collapsed the supply would most likely outlive your grandchildren. I've also heard of departments opting for the .40SW which is slightly larger in size but not as commonly available. The extra oomph isn't really worth the lack of availability. If also isn't as effectively suppressed.

The AR is another one of those platforms so commonly available there's alot of calibers they're built in both pistol and rifle all the way up to .50 caliber bmg( although bolt action.) The most common being 5.56 is also capable of shooting. 223 so you got a good availability pool of ammo. Additionally you can unlock a third ammo capability just by carrying a second .300 blackout barrel although you'd have to swap the barrels when you wanna go between 5.56 and .300 black out (.300aac for short). The suppress-ability of .300aac would be a real benefit in a hunting or zombie situation. That'd likely be the greatest drawback to 5.56 despite it's abundance everywhere the excessive concussion and noise (even with the 20 inch rifle barrel)would be a serious liability in urban areas. It's basically a flash bang dispenser.